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Symbols for built and powered things: circuit and fluid-power schematics, plant and building services, drawing and manufacturing notation, and the power and safety marks on equipment.
Here when the symbol appears in a technical drawing, a schematic or on the equipment itself. Software and interface icons are everyday and digital, even when the thing behind them is engineering.
Standardised through IEC, ISO and national drawing conventions, with a large body of common usage where practice has run ahead of the standard.
All 744symbols in this domain, A–Z.
A halving series of sheet sizes, from A0 at one square metre downward.
A number held in beads.
Cast lettering and a load class on a manhole or inspection cover.
A rounded vessel storing energy under pressure.
A restriction crossed by an adjustment arrow.
A shaft with blades, mixing a vessel's contents.
A circle with an open triangle pointing outward.
A vessel removing moisture from compressed air.
A rectangle housing fans, filters and coils.
A circle with an open triangle pointing inward.
A closed vessel storing compressed air.
Filter, regulator and lubricator grouped in one outline.
A tube bank with a fan drawn beneath it.
A small aeroplane silhouette, marking the setting that disables a device's radios.
A circle or a double circle on a leader, extending a callout.
The first Greek letter, used across science for angles, rates and particles.
A wavy line (∼) — IEC 60417-5032, indicating on a rating plate that equipment is suitable for alternating current.
A circle containing a capital A, measuring current.
A capital A, the SI unit symbol for the ampere.
An instrument bubble tagged for composition measurement.
Brazil's radio equipment approval.
A flat-backed D shape, outputting true only when every input is true.
An angle sign in a frame, controlling orientation to a datum.
A stem branching into two upward diagonals.
A band over a cork.
A comma-like mark splitting a number.
A notched rectangle, indented at the top centre.
Which side of the joint gets the weld.
A single winding with a tap, not two separate coils.
A head marked at a single point on the rail.
A valve bowtie with an open circle at its centre.
Longer bars marking a barcode's edges and centre.
Blank margin required either side of a code.
A dimension in a rectangle, exact by definition.
A long rounded rectangle with a drain mark.
A rectangle with a small nub at one end, filled in proportion to the charge remaining.
Letters and numbers naming a cell's physical size and chemistry.
Alternating long and short parallel lines, marking a cell or battery.
A straight-sided cylinder with a pouring lip.
A name cast into bronze.
Two parallel lines with end pulleys carrying solids.
The second Greek letter, used for beta particles, coefficients and angles.
Half a V.
A pump circle with two solid triangles pointing opposite ways.
Hinged leaves folding back against each other.
A line with two angled leads inside a circle, one carrying an arrow.
A line beyond the trim showing overprint.
A rotating machine outline moving gas at low pressure.
An angular rune-like glyph marking a Bluetooth wireless connection.
A name, a definition sign and alternatives.
The pressure it was built for.
A rectangle marked as the heat source of a system.
A wider tube for heating larger quantities.
A domed metal bolt set into masonry.
Numbers or radial lines on a head giving tensile strength.
A label claiming a book.
An H across a boundary showing shared responsibility.
A jagged or looped line marking omitted length.
A tank fitting admitting and venting air.
Diagonal hatching marking brickwork cut in section.
A permanent magnet set between the rails.
A black bar behind a white circular screen.
A colour light showing one of four aspects.
A row of white lights angled towards the route set.
A red bar sign marking the end of permitted movement.
A lineside board marking a gap in the supply.
Two white lights set at forty-five degrees.
A fishtailed arm warning of the signal ahead.
A square-ended arm that drops or rises to clear.
A white disc crossed by a red bar.
A board marking where a restriction begins.
A board marking where a restriction ends.
A small white light below a main aspect.
A yellow warning board ahead of a restriction.
An illuminated letter or number beside a signal.
A flat perforated plate above a stem.
A vertical casing with buckets on a loop.
A plain triangle passing its input through unchanged.
999.9, or 24K — how pure the metal is, stamped on the bar.
A vertical barrel on a base with a gas inlet.
A long graduated tube with a tap at its foot.
A valve bowtie with a diagonal disc line.
A number identifying a defined land parcel.
A number naming a movement.
The two letters cd, the SI unit symbol for the candela.
Two parallel lines across a break in a wire, marking a capacitor.
A wall opening with glazing lines and a swing arc.
A number burnt into oak.
A circle with crossed lines marking a light point.
A long-dash-dot line marking an axis of symmetry or a circle's centre.
A tapering outline compressing gas continuously.
A circle with a triangular wedge, marking a pump and its flow direction.
A bowl outline separating by spinning.
A running distance measured along a route.
One moving blade between two fixed contacts.
One contact that can meet either of two others.
A rake of three short diagonal strokes under a stem.
A ball or flap against a seat, permitting flow one way only.
A name pressed into the crust.
A switch drawn with a marking showing automatic operation.
A plain circle inside a tolerance frame.
Four digits in one figure.
A board and a bang, together.
A small square inside a larger square — IEC 60417-5172, marking equipment protected by double or reinforced insulation rather than an earth connection.
A valve centre square with all four ports blocked.
A rounded cloud outline, standing for a remote service or remote storage.
A line inside a partial enclosure, marking a screened conductor.
A dense barcode with three character sets.
A small black block on a section's spine, stepping down the book when gathered.
A strip of ink patches along a sheet edge, used to measure printing quality.
A lettered and numbered grid locating structure.
A looped square with four outward corners, marking the Mac command key.
A triangle like an op-amp but with a digital output.
A curve hollowed inward.
Two circles sharing a centre in a tolerance frame.
Scattered dots and triangles marking concrete in section.
Two numbers giving crushing strength at twenty-eight days.
A cone-shaped vessel with a narrow neck.
A rectangle marking the origin of an installation.
A relay coil driving heavy-current contacts.
Four letters and seven digits on steel.
Symbols for how to lift it.
A circle with a single horizontal line across it.
A valve body with an actuator drawn above it.
A curve bulging outward.
A diamond with arrows pointing outward, shedding heat.
A tapered outline with a fan and water lines.
A struck-through marginal instruction.
A rectangle marked CTR with a modulus number.
A valve holding back a load against gravity.
A flat-bottomed bracket shape, calling for a flat-bottomed enlarged hole.
A shallow V shape, calling for a conical widening at a hole's mouth.
Rods laid out in place columns.
Short right-angled lines at each corner, showing where a sheet is to be trimmed.
Two lines crossing without a dot, not connected.
Two lines crossing, one hopping over the other or plainly crossed.
A splayed end meaning many.
A crystal drawn with two capacitors to ground.
A small rectangle between two plates, marking a quartz frequency reference.
A circle with an arrow, delivering a set current.
A conductor passing through a ring winding.
A cylinder with a small rectangle marking end-of-stroke braking.
A cylinder above a cone, separating solids from gas.
A rectangle with a piston and rod showing how it acts.
A circle between two slanting lines in a tolerance frame.
A rectangle with D and clock inputs and Q outputs.
Two transistor symbols nested inside one outline.
A matrix code with an L-shaped finder.
A boxed letter on a filled or open triangle, establishing a reference.
A divided circle naming a point, line or area of contact.
The two letters dB, marking a ratio on a logarithmic scale.
A snowflake with a drop beneath it, or a snowflake being melted.
A degree sign followed by a capital C, marking a temperature in Celsius.
A clock face with an arrow, or the letter h with a number.
A delete loop with closing arcs.
The fourth Greek letter, meaning change or difference in almost every field.
A triangle marking three windings joined end to end.
A trapezoid widening towards the outputs.
A gate line beside a continuous channel line.
A downward arrow saying how deep a hole goes.
A sealed vessel with a plate above a drying agent.
A circle around an area, referring to a larger drawing.
A notched bar holding a valve in its selected position.
A circle with a diagonal stroke, marking a dimension as a diameter.
A valve body with a curved diaphragm line.
A triangle pointing at a bar, marking a diode.
Two collinear strokes fed from a central gap.
A solid line above a dashed line — IEC 60417-5031, indicating on a rating plate that equipment is suitable for direct current.
Adjacent boxes whose arrows show each switched position.
A tall vessel with internal lines marking trays.
A T-shaped piece carrying a thermometer.
A gap in a wall with a quarter-circle arc showing the swing.
A wall gap with two leaves and two opposing arcs.
A rectangle with a piston rod out both ends.
A downward arrow, usually above a horizontal bar or an open tray.
Continuous, dashed and chain lines each meaning something different.
Size, material and tip type stamped on the shank.
A letter E in a circle with a country number, marking a type-approved part.
Irregular hatching marking undisturbed ground.
Square brackets marking an optional part.
Braces marking a repeatable part.
Two uprights side by side.
An upward triangle above a horizontal bar.
A plug or lightning bolt with a car, marking a charging point.
A circle with an arrow pointing at the face to be drawn.
A light symbol marked for operation on power failure.
A dash-dot outline grouping components in one housing.
A machine-readable code linking to a product record.
A star inside a stylised label outline, marking energy-efficient products.
A gate line beside three broken channel segments.
An arrow turning down then left, marking the enter or return key.
The fifth Greek letter, conventionally a very small positive quantity.
Vertical strokes marking uneven spacing.
A circle enclosing three or four short radiating strokes.
Sent as eight dots run together.
A long rectangle with step lines and a direction arrow.
An arrow leaving a circle, marking the escape key.
A transponder fixed between the rails.
A board marking a signalling location without lights.
A board marking a limit of movement authority.
A ladder of coloured arrows from green to red, grading a product's energy efficiency.
An outline of a plug's pin pattern, identifying a charging connector type.
A shallow open dish for driving off liquid.
A circle with blades removing air from a room.
A three- or four-bladed fan: the air is being circulated.
A capital F, the SI unit symbol for the farad.
A large X in four quadrants.
A small flag saying the weld is made on site.
A flag meaning not in the shop.
A plain circle marking an instrument out in the plant.
A right triangle marking a weld in the corner of a joint.
Numbers printed along the perforations.
A stack of plates dewatering a slurry.
A diamond with a dashed line across its short axis.
A filter diamond with a check valve alongside it.
A small square marking a manual alarm point.
A duct fitting closing where a duct crosses a barrier.
A chamber outline with burner marks and a stack.
A truncated cone shown in two views, stating which projection convention a drawing uses.
A circle with one solid triangle pointing inward.
A circle with one solid triangle pointing outward.
A line narrowing at a point to restrict flow.
A wall opening with glazing lines and no arc.
A fitting with a hatched element stopping flame travel.
A parallelogram, specifying how flat a surface must be.
A bowed line marking a flexible connection.
A valve centre with actuator ports joined to tank.
A tank outline with an internal line for a moving roof.
A small square or circle marking a floor drain.
A block splitting one flow into two fixed proportions.
An instrument bubble tagged as a flow controller.
An instrument bubble tagged for flow transmission.
A small lettered circle joining flows.
A diamond with labelled exits.
An arrow joining one step to the next.
A slanted parallelogram.
A rectangle with doubled side bars.
A plain rectangle for an operation.
Shapes standing for kinds of step.
A rounded shape starting or ending a flow.
Solid, dashed and dot-dashed lines for working, pilot and drain.
A straight bar meaning dress it flat.
A dashed line outside the trim, showing where a sheet is folded.
A mark where two routes begin to conflict.
A circled F applying a tolerance to an unrestrained part.
A single yellow light warning of a stop.
Two red lights requiring an absolute stop.
Two yellow lights warning of a diverging route.
Two yellow lights with a figure below.
One red light, a stop that may be passed.
A circle, square or diamond on a pump and filler flap identifying the fuel.
An enclosure with a sliding sash and extraction.
A deeply founded pillar anchoring the levelling network.
Letters and numbers stating a fuse's current, speed and voltage.
A rectangle with a line through it, marking a fuse.
A circle with a G and a pointer arc.
The third Greek letter, used for gamma rays, functions and display response.
A graduated barrel with a free-moving plunger.
An accumulator oval divided by a bladder line.
Two triangles meeting at their points, the generic valve on a flow diagram.
A number tying a stone to a report.
A plan line showing a boundary's approximate position.
A rectangular box divided into cells, stating a geometric characteristic and its tolerance.
A board requiring traction power to be shut off.
A single red light meaning halt.
A single green light meaning proceed.
Green with a second green light below.
One head serving as both main and distant.
A board requiring the horn at a crossing.
A figure on a triangular or rectangular board.
A white triangle standing on its point.
A white board carrying angled bars.
A white H on a black rectangle.
A board requiring the pantograph to be lowered.
A board marking the limit of shunting.
Two white lights on a rising diagonal.
Two yellow lights on a diagonal.
Three white lights in a triangle.
A valve bowtie with a filled circle at its centre.
A stable ground mark used for satellite positioning.
A narrow tube with a scale along its length.
An arrow or an underlined dimension on a ream wrapper, showing paper grain.
An arrow saying which way the cloth runs.
A zigzag against the top of the square: the top element alone, at full heat.
Shapes naming how the joint edges are prepared.
Bracketed digits naming what follows.
Lines a hand cannot draw.
A shape with one half shaded: run the cycle on a partly filled machine.
A rectangle with a capital H and four terminals.
Three stacked horizontal lines that open a navigation menu.
A pump circle with a lever handle attached.
Helmet colours identifying roles on a construction site.
A circle or rectangle crossed by a zigzag, marking heat transfer between streams.
A diamond with arrows pointing inward, adding heat.
The sun, switched on and off.
The two letters Hz, the SI unit symbol for the hertz.
A line of short even dashes, showing an edge concealed behind material.
Concentric rings, a dashed outer ring, or a flame: which zone and what kind.
Chalk on a foot before shoeing.
A long rectangle with domed ends, lying on its side.
A tall rounded vessel storing heated water.
A serpentine line with a drain connection.
A tapered joint between two duct sizes.
A circle with angled blades.
A hatched band across a duct.
A ribbed double line.
A serpentine line across a duct.
A duct section with rising droplets.
A circle carrying a letter code.
A circle with a solid triangle pointing out of it.
A short stub with a cross, for connecting a gauge.
A circle with a plus and minus or a bar, holding a set voltage.
A plain rectangle with a symbol inside naming the function.
A MOSFET gate driving a bipolar transistor's collector and emitter.
A ladder pattern you must not cross.
A signal protecting a gated crossing.
A colour light head of three or four aspects.
A low signal governing shunting movements.
A figure on a lineside board.
A board marking the outer limit of a station.
A signal warning of the stop signal ahead.
A board marked W requiring the horn.
A row of humps or a filled rectangle in a wire, marking an inductor.
A square of information on a wall.
A coloured band or tag showing the period in which equipment was last inspected.
A date saying when it was last looked at.
A circle with letters and a number tagging a process instrument.
Patterned lines distinguishing pneumatic, electric and software signals.
Letters in an instrument bubble naming its function.
A soft looping line marking thermal insulation.
Alfa, Bravo, Charlie.
A small circle on a lead marking active-low behaviour.
A ringed note marking an upside-down type.
Two digits for dust and water.
A contact blade with a short bar marking a visible break.
A bold barcode inside a heavy frame.
Half a U.
A vertical head of up to five lamps.
A thickened bar across a watercourse.
A double line following a riverbank.
A toothed wheel joined to a circuit line.
A mast with radiating strokes at its head.
A point mark where water is drawn off.
A short barred line across a stream.
A mast carrying three angled blades.
A line broken by regular pylon ticks.
A derrick outline over a wellhead point.
Two rows of lamps giving a speed.
A numbered board beside the track.
A disc carrying a single character.
A field-effect transistor whose gate touches the channel.
Japan's industrial standard mark.
A rectangle with J, K and clock inputs.
A capital J, the SI unit symbol for the joule.
A filled dot where two wires are connected.
A grid ordered so neighbours differ by one.
A capital K, the SI unit symbol for the kelvin.
A key written as numbers.
The two-letter symbol kg, the SI unit symbol for the kilogram.
A crossed or straight pattern note specifying a gripping surface.
Korea's industrial standard mark.
A small tapered vessel for strong heating.
A cone above a narrow stem.
The eleventh Greek letter, used for wavelength, eigenvalues and anonymous functions.
A circle with a cross inside it, marking a lamp or indicator.
A number rating how dangerous a laser is to the eye.
Thin lines with arrows tying a note or a size to a feature.
A diode symbol with two arrows pointing away, marking a light-emitting diode.
A triangle or circle marking a stated height.
An instrument bubble tagged as a level controller.
An instrument bubble tagged for level transmission.
An E-shaped pattern reading height to a hundredth.
A short lever drawn against a valve block.
A tube within a water jacket, drawn sloping.
A rectangle with crossed diagonals marking a lift car.
A resistor in a circle with two arrows pointing at it.
A small circle with a short stroke on a wall.
A contact with a small roller or plunger drawn on its actuator.
A table that is a limit.
Shapes standing for boolean functions.
A rectangle opening into a trumpet shape.
A bracket pushing matter downward.
A vessel adding oil mist to an air stream.
The two letters lm, the SI unit symbol for the lumen.
The two letters lx, the SI unit symbol for the lux.
An S certifying electrical safety.
Corrections read left to right across a line.
A circled M allowing extra tolerance as a feature shrinks.
A word meaning grave and imminent danger.
A tall graduated cylinder on a wide base.
A curve meaning it must reach the back.
Weather compressed into one line.
A lower-case m, the SI unit symbol for the metre.
Digits printed in magnetic ink.
A circle on a stem, converting sound into signal.
Text too small to copy.
Painted or fixed points recording position underground.
Dots and dashes — and a timing relationship that the printed form hides.
A three-terminal transistor with a gate bar separated by a gap.
A circle containing the letter M, marking an electric motor.
A bracket pushing matter to the left.
A bracket pushing matter to the right.
The twelfth Greek letter, and the SI prefix for one millionth.
A trapezoid narrowing towards the output, with select inputs.
A dot beside one end of each of two coupled windings.
An AND gate with an inverting circle on its output.
A capital N, the SI unit symbol for the newton.
A wave-like mark of curved strokes, indicating a near-field communication point.
The top quadrant rating flammability.
The left quadrant rating health hazard.
The right quadrant rating reactivity.
The bottom quadrant carrying a letter code.
Stencilled lettering on an aircraft surface marking unsupported skin.
A decibel figure on a machine.
Three scales and a straight edge.
Letters on a reference line calling for a named inspection method.
An OR gate with an inverting circle on its output.
Coloured lights read by their angle.
A low signal head governing slow movements.
Rows of amber lights read by angle alone.
One lamp showing different colours in turn.
A triangle with a small circle at its point, inverting the input.
A perpendicular distance from a survey line.
The horseshoe-shaped capital letter used to denote the ohm, the SI unit of electrical resistance — visually identical to, but formally distinct from, the Greek letter omega.
A code such as 5W-30 giving an oil's cold and hot viscosity behaviour.
The last Greek letter, used for angular velocity — and the source of the ohm sign.
A valve centre square with all four ports joined.
A triangle pointing right with two marked inputs.
A colour that depends on the angle.
An LED facing a phototransistor inside one box.
A curved-back shield shape, outputting true when any input is true.
A horizontal bar above a broad arrow, cut into stone as a height reference.
A name for a rank of pipes.
Two short lines across a pipe, measuring flow by pressure drop.
A circle with two triangles and a limited-rotation arrow.
A tall vessel with a hatched or shaded internal zone.
One mark in the text, one in the margin.
Urgent, but nobody is dying.
Two slanting parallel lines in a tolerance frame.
A figure giving the measured area of a parcel.
The two letters Pa, the SI unit symbol for the pascal.
Two upright bars that suspend playback.
A foot pedal shape marking foot operation.
A tag that says a permission exists.
An upright T on a base line, specifying squareness to a datum.
A shallow flat dish with an overlapping lid.
Tokens moving between places.
The twenty-first Greek letter, used for the golden ratio and magnetic flux.
A diode with two arrows pointing towards it.
A transistor with two arrows pointing towards it.
A dashed line and rectangle marking pressure actuation.
A check valve with a pilot line able to force it open.
An in-line fitting with a mesh element catching debris.
A rectangle with closely spaced parallel lines.
A right-pointing triangle that starts playback.
A letter naming a socket pattern.
Letters naming national plug patterns.
A valve bowtie with a rectangle at its centre.
A rectangle on the line.
A cross marking a port closed off.
A pair of check valves with a relief.
A capped branch off a drain.
A chambered box on a drain run.
A circle marking a pipe running vertically.
A U-shaped bend in a drain line.
An adjustable valve holding a set downstream air pressure.
A sliding leaf disappearing into a wall cavity.
A box drawn beside a set of points.
A capacitor with one curved plate and a plus mark.
A plus, a minus, a bar or a chamfer showing which way round.
A small dated sticker on a plug or lead recording an electrical safety check.
A crossed circle limiting where a feature may sit.
A pump outline moving a fixed volume per stroke.
A machine-printed bar or dot pattern encoding a delivery point.
A resistor with an arrow touching it, marking a variable division of voltage.
A plain circle (◯) — IEC 60417-5008, marking the control position that disconnects power from the equipment.
A vertical bar (|) — IEC 60417-5007, marking the control position that places equipment into a fully powered state.
A vertical line inside an unbroken circle — IEC 60417-5010, marking a button that switches equipment between fully on and fully off.
A divided tub for pre-wash; a clock or a bolt for a fast cycle.
A circle on a stem with a pointer or letters, marking a pressure indicator.
A valve square held open, sensing downstream pressure.
An angled valve body with a spring above it.
An instrument bubble tagged for pressure transmission.
An adjustable restriction with a compensating element.
A closed rectangle holding fluid above atmospheric pressure.
An exchanger condensing vapour to liquid.
Line weight distinguishing main process flow from services.
A crossbar on posts carrying a line and a level.
A half-circle, open or closed, controlling a whole shape.
A circle inside a diamond, marking logic functions.
A circled P extending a tolerance zone beyond the part.
A signed and dated box on a proof, transferring responsibility for the content.
Sent as A and R run together.
Sent as A and S run together.
Sent as B and T run together.
Sent as K and N run together.
Sent as V and A run together.
A square in a square.
A circle enclosing a three-bar earth glyph — IEC 60417-5019, marking the protective earth (ground) terminal on Class I equipment.
Japan's electrical safety mark.
A small tee shape marking hand-button operation.
A contact operated by a stem with a bar on top.
Three letters standing for a whole sentence.
Three letters standing for a whole sentence.
Three letters standing for a whole sentence.
Three letters standing for a whole sentence.
Three letters standing for a whole sentence.
A square block of black and white cells with three large squares at its corners.
A small nested square within the code.
Three nested squares at the corners.
An alternating line of modules.
A three-port valve venting a cylinder locally.
Opposed brackets marking a connector that can be parted.
An address inside a building.
A long narrow rectangle against a wall.
A capital R before a dimension, marking it as a radius.
Instructions written to be rubbed out.
A short stub diverging from a running line.
A bracket lifting matter upward.
A four-digit number naming an industrial colour exactly.
A sloping surface with an arrow marking the rise.
A vessel outline marked as a place of reaction.
A square is the oven, lines are elements, a fan is forced air.
An exchanger returning vapour to a column base.
A cylinder and piston outline compressing gas in strokes.
A hook symbol or removable cover marking a vehicle's rated recovery point.
Two parallel lines carrying air, sized on the drawing.
A height calculated against a stated datum.
Two overlapping blades inside a small capsule outline.
One or two arrows curving into a near-closed circle, indicating reload or synchronisation.
A fine circle crossed by a full-length cross, used to align printing plates.
A plain rectangle in the control circuit, with a reference letter.
A coil beside a switch, showing a circuit that a second circuit operates.
A single box with an arrow and a spring, limiting pressure.
A breaker marked with a current-comparison box.
A rectangle with a diagonal line and a temperature label.
A zigzag or a plain rectangle in a circuit, marking a resistor.
A vertical rod on a heavy base with an adjustable clamp.
A square with inward lines drawing air back.
A scalloped outline around what has changed since the last issue.
A circle with radiating leaves in an opening.
The seventeenth Greek letter, used for density and resistivity.
A circle drawn round a written instruction.
A star or a sun for rinse aid, and an arrow into a container for salt.
A small circle on a stem, tripped by a passing part.
A spherical vessel with a narrow neck.
A stroke joining two paragraphs.
One or two slanting arrows controlling wobble about an axis.
A line with a bowed membrane, bursting to relieve pressure.
A transparent barrier between operator and apparatus.
A coloured tag at a scaffold access point recording its inspection status.
A buffer or gate containing a small hysteresis loop glyph.
A diode whose bar ends turn like a letter S.
A trough with a helical line moving solids.
Recess shapes naming how a fastener is turned.
A circle crossed by a bar.
A device that paints a radar screen.
A magnifying glass: a circle with a short diagonal handle.
Chile's electrical and fuel safety seal.
A lower-case s, the SI unit symbol for the second.
A heavy line with end arrows marking where a section is taken.
Diagonal lines showing solid material a cut has passed through.
A dial or droplet with a wave: the machine decides when to stop.
A pear-shaped vessel with a tap at the base.
A normally closed valve opening at a set inlet pressure.
A count that identifies one thing.
A motor circle with a feedback element attached.
A struck-through capital with a marginal note.
A ringed instruction cancelling a style.
A double underline beneath matter.
A driven peg marking a designed position on the ground.
A toothed wheel, marking a control that opens settings or preferences.
Three dots joined by two lines, or a box with an arrow leaving it, marking a share action.
A circle inside a square, marking a shared control system.
A cylinder with tube lines running through it.
A conductor within a dashed enclosing line.
A dashed rectangle around part of a circuit.
A hollow upward arrow, marking the shift key.
A long rectangle with SRG and a stage count.
A square tray with a drain and diagonal lines.
A ball in a tee, passing the higher of two pressures.
A conical flask with a tube on its neck.
An in-line fitting allowing flow to be seen.
Paired rails and a T-shaped staff controlling a gradient.
The eighteenth Greek letter, used for standard deviation and stress.
A solid downward triangle marking a common reference.
A shutter over a light.
A row of bars of increasing height, showing received signal strength.
A tapered outline on an exhaust port.
A rectangle with a piston rod out one end and one port.
A heavy line carrying connections.
A square drawn on a conductor line.
A hinged blade breaking a line.
A circle carrying a letter G.
Two overlapping circles on a line.
A transformer tapped off a conductor.
Numbers spaced by logarithm.
A wall gap with a leaf drawn parallel to the wall.
A tag that must be legible or the sling is scrap.
Coloured pitch on a fleece.
A circle marked S on a ceiling position.
A semicircle on a line, marking a power point.
A circle in plan marking a vertical drainage stack.
A battery cell symbol with two arrows pointing at it.
A coil marked as producing mechanical movement.
One bead above, four below.
Three dots, three dashes, three dots.
A number giving the distance across the flats.
A capital S before the diameter sign.
A circle with a coiled arrow, and a number in revolutions per minute.
Wedge-shaped treads radiating around a centre.
A circle on the line.
A zigzag spring returning a valve to its rest position.
An accumulator oval with a spring drawn inside.
A small circle marking a suppression outlet.
Two parallel uprights.
A small square before a dimension, marking a square feature.
A rectangle with set and reset inputs and no clock.
Parallel lines with an arrow marking direction of travel.
A vertical line entering the top of a broken circle — IEC 60417-5009, marking a control that puts equipment into a low-power state rather than fully disconnecting it.
Three lines meeting at a common point.
A marked callout permitting statistical rather than worst-case control.
Rising wavy lines, usually over a vessel.
A fitting discharging condensate but holding steam.
Letters and numbers naming composition and strength.
Close diagonal hatching marking structural steel.
A motor circle with multiple winding connections.
A rectangle with flat ends, holding liquid at atmosphere.
A single straight line inside a tolerance frame.
A resistor symbol with a diagonal arrow or a zigzag foil pattern.
Lines that are not evenly spaced.
A square with radiating lines delivering air.
A check-mark-like tick with a long arm, carrying surface texture requirements.
A mark saying which way the machining marks must run.
A tick with added bars and numbers specifying roughness.
Two stacked arcs.
A rectangle with an arrow through it, between line and earth.
A brass disc set in stone.
A break in a wire bridged by a hinged line, marking a switch.
Three horizontal lines in a tolerance frame.
A rectangle with a single T input and a clock.
A right-pointing arrow meeting a vertical bar, marking the tab key.
The same grammar, in the future tense.
A drum that follows the tones of speech.
A valve centre with pump joined to tank and ports blocked.
Two shallow triangles distinguishing a cone from a wedge.
Nested rectangles showing a multi-stage ram.
An instrument bubble tagged as a temperature controller.
An instrument bubble tagged for temperature transmission.
A local reference height set for one job.
A small hollow circle where a wire can be connected.
A capital T, the SI unit symbol for the tesla.
A small marked node intended for measurement.
A narrow tube closed with a rounded end.
A figure drawn from a measured grid.
A resistor crossed by a line marked with a temperature sign.
Two dissimilar lines meeting at a junction point.
The eighth Greek letter, the default name for an angle.
A truncated cone in two views, mirrored from the first-angle symbol, stating the American convention.
A long tube with a bulbous flared top.
A letter code and numbers naming a screw thread completely.
Three lines with a numeral and phase notation.
Three squares side by side with four connections.
A valve body with three connections instead of two.
A diode with a gate lead, latching once triggered.
A stamp giving strength class, moisture and certification.
Grain lines marking sawn timber cut across.
A bracketed section of a drawn track line.
Two coils facing each other across parallel lines, marking a transformer.
An arrow on one lead showing the device's polarity.
A numbered ground mark in a survey traverse.
A triangle with a control line entering its flat side.
Two thyristors drawn back to back with one gate.
A three-legged stand with a mesh square on top.
Two lines crossing each other repeatedly.
Two squares side by side with two connections.
A switch symbol marked for control from two points.
Two round pins without an earth.
Three rectangular pins with a fuse.
Two angled flat pins with an earth.
A number and a letter after the size, giving load capacity and maximum speed.
A coded string on a sidewall giving width, profile, construction and rim size.
A U on the line.
A narrow rectangle on a lifeline.
A stick figure standing for a role.
A line ending in a hollow diamond.
A plain line joining two classes.
A rectangle divided into three bands.
A line ending in a filled diamond.
A dashed line with an open arrowhead.
A line ending in a hollow triangle.
A dashed vertical line below a participant.
Figures at the end of an association line.
An oval containing a goal.
A sign prefixing a member name.
A serpentine line covering a floor area.
Coloured printed tape laid above a buried cable or pipe as a last warning.
A valve returning pump flow to tank at low pressure.
An upward arrow, usually above a horizontal bar or an open tray.
A trident of three branches ending in a circle, a triangle and a square, marking a USB port.
A flattened oval outline, marking a USB Type-C port.
Sprayed letters and figures giving a buried service's size, material and depth.
Coloured paint before you dig.
A post above a buried line.
Spray-painted colours on a road surface, each standing for a buried service.
A V on the line.
A converging nozzle producing suction from air flow.
A cup shape gripping a workpiece by suction.
A capacitor with an arrow drawn across its plates.
A motor circle crossed by a diagonal arrow.
A pump circle crossed by a diagonal arrow.
A resistor marked with a voltage-dependence stroke.
Seventeen characters, one of them a check.
An open-topped rectangle holding the system fluid.
A tall rectangle with domed ends, drawn upright.
A capital V, the SI unit symbol for the volt.
A circle containing a capital V, measuring potential difference.
A duct fitting adjusting the air passing through.
A pear-shaped vessel with a single graduation line.
A tube with a central bulb and one graduation.
A circle for calibrating a receiver.
A rounded bowl outline against a wall.
A squeeze bottle with a bent delivery tube.
A shallow circular dish used as a cover or surface.
A rounded pan outline with a cistern behind it.
A graded scale rating water consumption.
A capital W, the SI unit symbol for the watt.
A circle with a W and four terminals.
Four linked grids specifying threading, tie-up, treadling and the resulting cloth.
An accumulator with a weight drawn above the piston.
Which side of the reference line a weld symbol sits on.
A line and letter saying what shape the finished weld must be.
A code in the tail of a welding symbol naming the process.
A circle meaning go right round.
A circle at the reference line's elbow, calling for a continuous weld.
The line every weld symbol hangs on.
An arrow and horizontal reference line carrying weld type, size and process.
A fork carrying the process.
Nested arcs radiating from a dot, indicating a wireless network signal.
A small semicircular hop where wires cross without joining.
A number that gets larger as the wire gets thinner.
A curved-back shield with a second arc and an output bubble.
An OR gate with a second curved line across its back.
A diode whose bar has bent ends like a letter Z.